Merge pull request #3798 from bclothier/EventInterface

Provide a method of pumping COM objects in a synchronous block (no user-facing changes)

Author: retailcoder

RetailCoder.VBE/API/VBA/ParserState.cs

@@ -56,6 +56,7 @@ public sealed class ParserState : IParserState, IDisposable
         public ParserState()
         {
             UiDispatcher.Initialize();
+            ComMessagePumper.Initialize();
         }
 
         public void Initialize(Microsoft.Vbe.Interop.VBE vbe)

RetailCoder.VBE/App.cs

@@ -13,6 +13,7 @@
 using Rubberduck.Parsing.Inspections.Resources;
 using Rubberduck.Parsing.UIContext;
 using Rubberduck.UI.Command;
+using Rubberduck.VBEditor.ComManagement;
 using Rubberduck.VBEditor.SafeComWrappers.Abstract;
 using Rubberduck.VersionCheck;
 using Application = System.Windows.Forms.Application;
@@ -50,6 +51,7 @@ public App(IVBE vbe,
             _configService.SettingsChanged += _configService_SettingsChanged;
 
             UiDispatcher.Initialize();
+            ComMessagePumper.Initialize();
         }
 
         private void _configService_SettingsChanged(object sender, ConfigurationChangedEventArgs e)

Rubberduck.Parsing/UIContext/UiDispatcher.cs

@@ -98,8 +98,7 @@ public static Task<T> StartTask<T>(Func<T> func, TaskCreationOptions options = T
         {
             return StartTask(func, CancellationToken.None, options);
         }
-
-
+        
         private static void CheckInitialization()
         {
             if (UiContext == null) throw new InvalidOperationException("UiDispatcher is not initialized. Invoke Initialize() from UI thread first.");

Rubberduck.VBEEditor/ComManagement/ComMessagePumper.cs

@@ -0,0 +1,54 @@
+using System;
+using System.Threading;
+using Rubberduck.VBEditor.ComManagement.VBERuntime;
+
+namespace Rubberduck.VBEditor.ComManagement
+{
+    public static class ComMessagePumper
+    {
+        private static SynchronizationContext UiContext { get; set; }
+        private static readonly Lazy<IVBERuntime> Runtime = new Lazy<IVBERuntime>(() => new VBERuntimeAccessor());
+
+        public static void Initialize()
+        {
+            if (UiContext == null)
+            {
+                UiContext = SynchronizationContext.Current;
+            }
+        }
+
+        /// <summary>
+        /// Used to pump any pending COM messages. This should be used only as a part of
+        /// synchronizing or to effect a block until all other threads has finished with 
+        /// their pending COM calls. This should be used by the UI thread **ONLY**; 
+        /// otherwise execptions will be thrown. This is mandatory when the COM objects are
+        /// STA which would otherwise deadlock in other threads. 
+        /// </summary>
+        /// <remarks>
+        /// Typical use would be within a event handler for an event belonging to a COM 
+        /// object which require some synchronization with COM accesses from other threads. 
+        /// Events raised by COM are on UI thread by definition so the call stack originating
+        /// from COM objects' events can use this method.
+        /// </remarks>
+        /// <returns>Count of open forms which is always zero for VBA hosts but may be nonzero for VB6 projects.</returns>
+        public static int PumpMessages()
+        {
+            CheckContext();
+
+            return Runtime.Value.DoEvents();
+        }
+
+        private static void CheckContext()
+        {
+            if (UiContext == null)
+            {
+                throw new InvalidOperationException("UiSynchronizer is not initialized. Invoke Initialize() from UI thread first.");
+            }
+
+            if (UiContext != SynchronizationContext.Current)
+            {
+                throw new InvalidOperationException("UiSynchronizer cannot be used in other threads. Only the UI thread can call methods on the UiSynchronizer");
+            }
+        }
+    }
+}

Rubberduck.VBEEditor/ComManagement/VBERuntime/IVBERuntime.cs

@@ -0,0 +1,8 @@
+namespace Rubberduck.VBEditor.ComManagement.VBERuntime
+{
+    internal interface IVBERuntime
+    {
+        float Timer();
+        int DoEvents();
+    }
+}

Rubberduck.VBEEditor/ComManagement/VBERuntime/VBERuntime6.cs

@@ -0,0 +1,23 @@
+using System.Runtime.InteropServices;
+
+namespace Rubberduck.VBEditor.ComManagement.VBERuntime
+{
+    internal class VBERuntime6 : IVBERuntime
+    {
+        private const string DllName = "vbe6.dll";
+
+        [DllImport(DllName)]
+        private static extern int rtcDoEvents();
+        public int DoEvents()
+        {
+            return rtcDoEvents();
+        }
+
+        [DllImport(DllName)]
+        private static extern float rtcGetTimer();
+        public float Timer()
+        {
+            return rtcGetTimer();
+        }
+    }
+}

Rubberduck.VBEEditor/ComManagement/VBERuntime/VBERuntime7.cs

@@ -0,0 +1,23 @@
+using System.Runtime.InteropServices;
+
+namespace Rubberduck.VBEditor.ComManagement.VBERuntime
+{
+    internal class VBERuntime7 : IVBERuntime
+    {
+        private const string DllName = "vbe7.dll";
+
+        [DllImport(DllName)]
+        private static extern int rtcDoEvents();
+        public int DoEvents()
+        {
+            return rtcDoEvents();
+        }
+
+        [DllImport(DllName)]
+        private static extern float rtcGetTimer();
+        public float Timer()
+        {
+            return rtcGetTimer();
+        }
+    }
+}

Rubberduck.VBEEditor/ComManagement/VBERuntime/VBERuntimeAccessor.cs

@@ -0,0 +1,75 @@
+using System;
+
+namespace Rubberduck.VBEditor.ComManagement.VBERuntime
+{
+    public class VBERuntimeAccessor : IVBERuntime
+    {
+        private enum DllVersion
+        {
+            Unknown,
+            Vbe6,
+            Vbe7
+        }
+
+        private static DllVersion _version;
+        private readonly IVBERuntime _runtime;
+        
+        static VBERuntimeAccessor()
+        {
+            _version = DllVersion.Unknown;
+        }
+
+        public VBERuntimeAccessor()
+        {
+            switch (_version)
+            {
+                case DllVersion.Vbe7:
+                    _runtime = new VBERuntime7();
+                    break;
+                case DllVersion.Vbe6:
+                    _runtime = new VBERuntime6();
+                    break;
+                default:
+                    _runtime = DetermineVersion();
+                    break;
+            }
+        }
+
+        private static IVBERuntime DetermineVersion()
+        {
+            IVBERuntime runtime;
+            try
+            {
+                runtime = new VBERuntime7();
+                runtime.Timer();
+                _version = DllVersion.Vbe7;
+            }
+            catch
+            {
+                try
+                {
+                    runtime = new VBERuntime6();
+                    runtime.Timer();
+                    _version = DllVersion.Vbe6;
+                }
+                catch
+                {
+                    // we shouldn't be here.... Rubberduck is a VBA add-in, so how the heck could it have loaded without a VBE dll?!?
+                    throw new InvalidOperationException("Cannot execute DoEvents; the VBE dll could not be located.");
+                }
+            }
+
+            return _version != DllVersion.Unknown ? runtime : null;
+        }
+
+        public float Timer()
+        {
+            return _runtime.Timer();
+        }
+
+        public int DoEvents()
+        {
+            return _runtime.DoEvents();
+        }
+    }
+}

Rubberduck.VBEEditor/Rubberduck.VBEditor.csproj

@@ -129,7 +129,12 @@
     <Reference Include="System.Windows.Forms" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="ComManagement\ComMessagePumper.cs" />
     <Compile Include="ComManagement\TypeLibs\IVBETypeLibsAPI.cs" />
+    <Compile Include="ComManagement\VBERuntime\IVBERuntime.cs" />
+    <Compile Include="ComManagement\VBERuntime\VBERuntime6.cs" />
+    <Compile Include="ComManagement\VBERuntime\VBERuntime7.cs" />
+    <Compile Include="ComManagement\VBERuntime\VBERuntimeAccessor.cs" />
     <Compile Include="ComManagement\WeakComSafe.cs" />
     <Compile Include="ComManagement\ComSafeManager.cs" />
     <Compile Include="ComManagement\IProjectsProvider.cs" />